Field of the Invention
The present invention relates to aqueous emulsion pressure sensitive adhesive (PSA) compositions useful with facestocks and/or packaging labels designed to be removed in the recycling of polymeric packaging.
Description of the Related Art
In recent years, use of polymeric packaging (e.g. polyethylene terephthalate (PET), high density polyethylene (HDPE), polyvinyl chloride (PVC), polypropylene (PP), or other plastic types) has increased due to their lightweight and break resistance. Pressure sensitive filmic labels have also grown in usage with polymeric packaging systems due to improved moisture resistance and appearance, and the ability to recycle such packaging materials is desirable. During a typical recycling process, a hot caustic bath containing surfactant is used to release the ground plastic flake from the label. Subsequently the plastic flake is separated in a sink-float process from the removed label. The Association of Postconsumer Plastic Recyclers (APR) have established protocol for evaluating labeling systems for recyclability. Failure to remove the filmic labels in the recycling process taints the color and reduces the clarity of recycled PET.
Filmic labels are more resistant to the recycling conditions which leads to a portion of the label still attached at the end of the process. Therefore, it would be desirable that the filmic label and adhesive be designed to release in the washing step of the recycling process, and to separate from the PET in a liquid, showing a specific gravity allowing for floating or sinking of the separated components.
Accordingly, there is a need for a pressure sensitive adhesive (PSA) for filmic labels that can facilitate separation in the recycling process while maintaining the desired performance properties through the article's life cycle.
There is also a need in the art for polymeric packaging systems that can provide for a recycling process which is efficient and cost effective.